Background
The airstrip was situated on a knoll approximately 300 feet above the surrounding terrain. It was about 900 feet long and sloped downhill at an angle of roughly 2 degrees. At the time of departure, the wind was reported by the pilot as generally from the west at 12 knots with gusts to 15 knots, but varying direction from northwest to southeast. The airplane was 31 pounds below its maximum gross weight.
Takeoff Attempt
The pilot initiated a takeoff roll to the south. At an airspeed of approximately 50 mph, he attempted to rotate the airplane for takeoff. The airplane did not rotate as expected; instead, it became airborne as it continued off the departure end of the airstrip.
Accident Sequence
After departing the airstrip, the pilot attempted to gain airspeed by lowering the nose of the airplane as it descended toward the lower terrain below the knoll. The airplane subsequently struck several trees about 200 yards from the end of the airstrip.
Pilot's Report
The pilot reported that during the departure, the airplane encountered an unexpected tailwind or downdraft.